Felted fibrous cellulosic structural board having rigidified portion and method of making same



United States PatentOfiFice Patented Aug. 30, 1955 FEE/TED FIBROUS CELLULOSIC STRUCTURAL BOARD HAVING .RIGIDIFIED PORTION AND METHOD F MAKKNG-SAME Herbert F. Austin, -Jr., Great Neck,'Moses Konigsberg, Roslyn, John M. Morrison, New York, and Frank C. Campins, Pelha'm, 'N. 35., assignors, "by direct and mesne assignments, to Jam, Wichita, .Kans., apartnership NoDrawing. ,APPlication February'7,'1951,

Serial No; 209,916

12 Claims. (Cl. 117-37) This invention relates to rigidified fibrous articles, and the method of forming and'imparting additional rigidity to such materials.

The use of board and other architectural forms fabricated from fibrous materials is well known. However, the extent to whichthese materialshave been employed has been limited by the lack of rigidity inherent in their structure. Efforts have been made to impart rigidity to fibrous materials-by bonding sheets of aluminum or some other rigid substances to them. The resulting-structures have been both expensive and in many cases unsatisfactory from the standpoint of weight, cost and permanence.

Accordingly, it is an object of the present invention to provide a rigidified fibrous material having great structural strength.

Another object of the present invention is to provide an inexpensive rigid structural material.

A further object of the present invention is to provide a fiber board having properties whichwill adapt it as a substitute for plywood, hard board or wood.

An object of the present invention is to cause fiber board to rigidify bythe introduction of the composition material.

A feature of the present invention properties.

Another feature of this properties.

A further feature of this invention is the abilityof the rigidified board to support itself structurally, with a minimum amount of bracing, thereby extending its usefulness as a building material.

A feature of the present invention is its capacity for being shaped as desired.

In the manufacture of rigidified fiberboard and the like, in accordance with the present invention, a long fibered product, such as is sold under the trade name Celotex is preferred as the base material. However, any porous cellulosic material is suitable. "In its untreated state this material lacks structural strength and is porous. These characteristics render is unsuitable for most building, packaging and other'applications. -It has been'found, however, that by the application of suitable rigidifying compositionshereinafter described in'the manner set forth below, a highly superior article may be formed from the base material.

The rigidifying compositions may be applied by dipping, spraying, rolling or flooding them upon the base material. Each method of application'has certain advantages as to depth of penetration,economy, speed, etc., but their common purpose is to impregnate the fibers-of the board with the composition.

The depth of penetrationof the compositions into the board may be further regulated by the formulation of the is its fire retarding invention is its weight saving composition; the amount of fluid of time of such application.

Preheating of the 'fiber board prior to thejapplication of the rigidifying compositions has alsobeen found useful in governing the speed and depth of penetrationof the rigidifying material. Increased depth of penetration has been achieved in some instances by applying the rigidifying material to the fiber in a vacuum.

After the fibers have absorbed the desired amountof the rigidifying composition,'the board maybe dried either in air or by the use of heat in the form of hot air, infra.- red heat or the like.

The rigidified board may then be'sized, coated, surface finished, colored or decorated, as desired. It maybe sanded and polished to form an attractive flooring. ma: terial having the appearance and .feel. of cork.

One of the preferred forms of rigidifying compositions consists of the following: I

applied and the period Parts- Urea-formaldehyde resin solution (aqueous) Wetting agent t 2 Resin emulsion (or dispersion) 10 Highly suitable wetting agents were found-tobe nonionic penetrants such as TritonN. -E. (aryl alkyl polyether alcohol) is concentrations-of from /2 to 10.parts.depending upon the desired concentration of the impregnating formula.

A preferred resin emulsion is a polystyrene emulsion of 40%. solidscontent. While the rigidifying composition is suitable for certain purposes without the resin-dispersion, greater toughness and better aging properties are obtained with it.

Among the other suitable dispersions-which may be used in connection 'with the rigidifying :composition are:- natural rubber latex; syntheticlatices of all kinds; vinyl chloride andvinyl acetate dispersions; polyisobutylene;

It is necessary for the efiicient operation of the composition to employ a wetting'agent. The wetting agent increases the depth and speed of penetration of the -'compositioninto the fibers, -so as to make the'structure rigid core within the finished material of any desired thickness.

Water-repelling properties may be given the finished board, using water repellant agents such asjalurninum formate, aluminumacetate, zirconium or titanium salts, with all ofthe compositions described herein, byapply: ing said water-repelling agents before the compositions have completely dried.

A second form of rigidifying solution, according to the present invention, comprises:

Parts Polyvinylacetate emulsion 100 Wetting agent 1.25

The polyvinyl acetate emulsion used in this formula, which comprises the resin dispersion, is preferably a 55% solids fiber board, however, a resin dispersiongrade having two special characteristics, i. e. very small particle size and low viscosity. Water may be added to further reduce the viscosity of the resin dispersion.

Suitable wetting agents for use in connection with this formula are sulfated fatty alcohols, such as the Duponols. However, compatability and effectiveness in increasing penetration may govern the choice of the wetting agent, which may be applied in concentrations of /2 to 10 parts, depending upon the desired concentration of the impregnated compound.

Where desired, additional preservatives may be added to the rigidifying compound, such as Shirlan Extra (salicylanilide), or defoamers such as silicones and higher alcohols.

A third rigidifying composition within the purview of the present invention consists of:

Parts Zein 5 6 Resin 22.4 Plasticizer 16.8 Solvent 157 The zein (a corn protein, alcohol soluble fraction) is a film-forming resinous material. However, the present disclosure is not confined to zein, since other film-formers would work.

The resin may be chosen from any which are com patible with the film-forming resinous material selected. Highly satisfactory results were obtained with zein and Alpha V-40 (a resin derived from alpha pinene). The function of the resin is to add adhesion and solids to the film-former.

The nature and proportions of the plasticizer may be governed by the specific requirements sought. In some instances the plasticizer may even be omitted. A suitable plasticizer is Santicizer 8 (a mixture of methyl orthoand para-toluene sulfonamides).

The solvent may comprise alcohol to which may be added a small quantity of acetone and water, and perhaps toluene.

The advantages of the solvent-type composition are that it will penetrate deeply because of low surface tension and because it will not swell cellulose fibers, and also that it becomes waterproof without curing.

The rigidified fibrous material can be shaped as desired while it is in the wet state after having been impregnated with the above-described compositions. In those cases where thermoplastics are contained in the rigidifying compositions, the fibrous material may be shaped even after drying.

From the foregoing, it will be seen that there has been provided a rigidified fibrous article having, in addition to the advantages of light weight, insulating properties and economy inherent in such materials, qualities of fire retardation, waterproofing and structural strength, which have previously been unknown in the art.

The fiber board made in accordance with the present disclosure is easily shaped in manufacture. It may be made with ornamental finishes and in a large variety of types, so as to be adaptable as an economical substitute for many well known building materials, such as plywood, hardwood or wood. The rigidified material has applications as roof decking, concrete form liners, interior wall finishes, ceiling tiles, floor tiles and sub-flooring, for which the ordinary fiber board is unsuitable.

Having thus fully described the invention, what is claimed as new and desired to be secured by Letters Patent of the United States, is:

1. A fibrous, felted, cellulosic, structural board having at least a portion of the surface thereof rigid, said rigid portion extending inwardly from the surface of the board for a substantial depth, and a porous, soft, untreated portion beneath the rigid part, said rigid por tion consisting of the porous, soft board impregnated with a high concentration of a resin, said resin having been applied to the preformed soft porous board from a resin dispersion containing a wetting agent.

2. A fibrous, felted, cellulosic, structural board having at least a portion of each surface thereof rigid, said rigid portion extending inwardly from each surface of the board for a substantial depth, and a porous, soft, untreated core portion, said rigid portion consisting of the porous soft board impregnated with a high concentration of a resin, said resin having been applied to the preformed soft, porous board from a resin dispersion containing a wetting agent.

3. A fibrous, felted, cellulosic, structural board having at least a portion of the surface thereof rigid, said rigid portion extending inwardly from the surface of the board for a substantial depth, and a porous, soft, untreated portion beneath the rigid part, said rigid part consisting of the porous soft board impregnated with a high concentration of a synthetic resin, said resin having been applied to the preformed soft porous board from a synthetic resin latex dispersion containing a wetting agent.

4. A fibrous, felted, cellulosic, structural board having at least a portion of the surface thereof rigid, said rigid portion extending inwardly from the surface of the board for a substantial depth, and a porous, soft, untreated portion beneath the rigid part, said rigid part consisting of the porous soft board impregnated with a high concentration of polyvinyl acetate, said polyvinyl acetate having been applied to the preformed soft, porous board from a polyvinyl acetate dispersion containing a wetting agent.

5. A fibrous, felted, cellulosic, structural board according to claim 1 in which the wetting agent is a sulfated fatty alcohol.

6. A fibrous felted cellulosic structural board according to claim 2 in which the wetting agent is a sulfated fatty alcohol.

7. A fibrous felted cellulosic structural board according to claim 1 in which the resin is characterized by its small particle size.

8. A fibrous felted cellulosic structural board according to claim 1 in which the resin is characterized by its low viscosity and the dispersion is one having a high solids concentration.

9. A fibrous, felted, cellulosic, structural board having at least a portion of the surface thereof rigid, said rigid portion extending inwardly from the surface of the board for a substantial depth, and a porous, soft, untreated portion beneath the rigid part, said rigid portion consisting of the porous, soft board impregnated with a high concentration of a resin, said resin having been applied to the preformed soft, porous board from a small particle size, low viscosity resin dispersion having a high solids concentration and containing a wetting agent.

10. A process for preparing a rigidified, fibrous, felted, cellulosic, structural board which comprises applying to surface portions of a preformed, porous, soft board a sufiicient amount of a high penetrating small particle size, low viscosity, and high solids concentration resin dispersion to produce upon drying in said board a rigid portion, extending from the surface inwardly for a substantial depth in the area of said application.

11. A process for preparing a shaped rigidificd, fibrous, felted, cellulosic, structural board which comprises applying to surface portions of a preformed, porous, soft board a sufficient amount of a high penetrating small particle size, low viscosity, and high solids concentration resin dispersion to produce upon drying in said board a rigid portion, extending from the surface inwardly for a substantial depth in the area of said application and shaping said board while wet.

12. A process for preparing a rigidified, fibrous, felted, cellulosic, structural board which comprises applying to surface portions of a preformed, porous, soft board a suflicient amount of a high penetrating small particle size, low viscosity, and high solids concentration resin disper- 75 sion to produce upon drying in said board a rigid portion,

a soft, internal, untreated, core portion within the board.

References Cited in the file of this patent UNITED STATES PATENTS Chamberlain Nov. 3, 1925 Beckman July 24, 1934 6 Miller June 2, 1936 Frolich et a1. Nov. 24, 1936 Richter Dec. 28, 1937 Thompson et a1 Dec. 23, 1941. Lurie Aug. 17, 1943 Whitehead Sept. 28, 1943 Kvalnes et a1. Oct. 26, 1948, Roman Dec. 11, 1951 

10. A PROCESS FOR PREPARING A RIGIDIFIED, FIBROUS, FELTED, CELLULOSIC, STRUCTURAL BOARD WHICH COMPRISES APPLYING TO SURFACE PORTIONS OF A PREFORMED, POROUS, SOFT BOARD A SUFFICIENT AMOUNT OF A HIGH PENETRATING SMALL PARTICLE SIZE, LOW VISCOSITY, AND HIGH SOLIDS CONCENTRATION RESIN DISPERSION TO PRODUCE UPON DRYING IN SAID BOARD A RIGID PORTION, EXTENDING FROM THE SURFACE INWARDLY FOR A SUBSTANTIAL DEPTH IN THE AREA OF SAID APPLICATION. 